1. Field of the Invention
The present invention relates to a pixel structure and a liquid crystal display, and particularly relates to a pixel structure and a liquid crystal display with favorable display quality.
2. Description of Related Art
As the sizes of liquid crystal displays become larger, the demand for liquid crystal displays with high contrast ratio, rapid response, and wide viewing angle is increasing. To solve the problem of the large-sized liquid crystal display panels limited viewing angle, the technology of wide viewing angle needs to be improved. Liquid crystal display panels of multi-domain vertical alignment mode (MVA mode), such as multi-domain vertical alignment (MVA) liquid crystal display panels and polymer stabilized alignment (PSA) liquid crystal display panels, are common examples of wide viewing angle technology.
The conventional MVA mode liquid crystal display panel changes the direction of an electric field through alignment protrusions and/or alignment slits located on a color filter substrate or a thin film transistor array substrate. Thereby, the liquid crystal molecules are controlled to tilt in various directions so as to increase the viewing angle of the liquid crystal display.
FIG. 1A is a schematic cross-sectional view of a conventional MVA mode liquid crystal display panel, and FIG. 1B is a schematic top view illustrating a pixel structure of the conventional MVA mode liquid crystal display panel in FIG. 1A. Referring to FIGS. 1A and 1B, the conventional MVA mode liquid crystal display panel 1 comprises a first substrate 10, a second substrate 20, an alignment structure 30, and a liquid crystal layer 40. Each pixel on the first substrate 10 comprises an active device 14 and a pixel electrode 12 connected with the active device 14. The second substrate 20 is disposed above the first substrate 10 with an intervening cell-gap between the second substrate 20 and the first substrate 10. In addition, the second substrate 20 has a common electrode 22. In the MVA mode liquid crystal display panel 1, the alignment structure 30 may be fabricated on the first substrate 10 and the second substrate 20. Referring to FIG. 1A, the alignment structure 30 comprises alignment protrusions 32 on the second substrate 20 and alignment slits 34 on the pixel electrode 12. In addition, the liquid crystal layer 40 is disposed between the first substrate 10 and the second substrate 20.
As shown in FIG. 1B, the pixel electrode 12 is divided into four alignment domains which are a first alignment domain 12a, a second alignment domain 12b, a third alignment domain 12c, and a fourth alignment domain 12d. The alignment slits 34 in the first alignment domain 12a have a plurality of first alignment slits 34a parallel with one another. The alignment slits 34 in the second alignment domain 12b have a plurality of second alignment slits 34b parallel with one another. The alignment slits 34 in the third alignment domain 12c have a plurality of third alignment slits 34c parallel with one another, and the alignment slits 34 in the fourth alignment domain 12d have a plurality of fourth alignment slits 34d parallel with one another.
It is noted that the alignment slits 34 are symmetrically arranged, specifically, the first alignment slits 34a and the second alignment slits 34b are mirror images to each other. Further, the first alignment slits 34a and the second alignment slits 34b are mirror images to the third alignment slits 34c and the fourth alignment slits 34d. 
In addition, the liquid crystal molecules of the MVA mode liquid crystal display panel 1 are vertically aligned, and the alignment structure 30 controls the liquid crystal molecules in different domains to tilt in different directions so as to achieve the wider viewing angle. The alignment slits 34 are symmetrically arranged, and the liquid crystal molecules of each pixel should also be arranged symmetrically. However, the liquid crystal molecules in the center of different pixels are arranged asymmetrically, which causes the pixels to have discrepant brightness when displaying the same gray-level image. As a consequence, the display quality of the conventional MVA mode liquid crystal display 1 is poor.